Given the fact that the graphic user interface for computers and the like has been in use for less than two decades, it is somewhat surprising that so many of the common furnishings of the most popular graphic interfaces have become so familiar. Indeed, features such as pulldown menus and a window for each program or document that is open, are tools that computer users expect to be provided in any consumer or commercial application.
In a general sense, a window displayed in a graphical user interface is a rectangular display space bounded by a border. Typically, the size of the window may be altered by dragging one corner inwardly or outwardly, or clicking on a marquee button that shrinks or expands the window size. When the window display space is smaller than the document or object it is displaying, it is typical for a window to automatically provide a scroll bar. The scroll bar is comprised of a narrow rectangular box extending vertically and/or horizontally at the edge of the window, and a smaller rectangular “button” disposed in the box and adapted to be clicked and dragged longitudinally along the narrow box, in the manner of a slider button constrained in a channel or track. The length of the track represents the entire length (or width) of the thing being displayed, and the position of the button on the track provides an intuitive indication of the portion of the thing that is currently displayed in the window.
Consumer demand has led to the introduction of enhancements to the scroll bar concept. Up and down arrows at one or both ends of each scroll track can be used to scroll incrementally (line-by-line, for example), and a mouse scroll wheel enables rolling/scrolling motion by the user when the mouse cursor is on the track. Also, some applications employ a scaled size scroll button, in which the longitudinal dimension of the button is approximately proportioned to the ratio of the window display length (or width) to the length (or width) of the thing being displayed. These features enable the user to assert precise control of the scrolling process.
Aside from microcontrol of scrolling, another problem presented by scroll bars involves navigation within a document, particularly a large document. For example, a word processing document may have tens or hundreds of pages, and editing such a document may require cutting and pasting throughout the document, style changes or rewriting at designated places, and the like. Marking, finding, and keeping track of locations within a large document are tasks that scroll bar embodiments known in the prior art are not designed to carry out. In some applications, dragging the scroll button causes an adjacent box to display the current page number, so that the user may know how far to drag the button to arrive at a particular page. However, the user must rely on other external organizing tools to be efficient in editing or revising a large document.
As noted above, every scroll bar includes an opaque track on which the scroll button is slidable. Thus each window presented onscreen includes opaque margins at the bottom and sides that are approximately ¼ inch (0.6 cm) wide, obscuring a small but not insubstantial portion of the display. When several windows are presented onscreen simultaneously, the reduction in object display area caused by the sum total area of the scroll bars of the windows may become significant. It is desirable to reduce this waste of display space, if possible.